-LRB- CNN -RRB- Amsterdam 's Rijksmuseum , one of the world 's best-known galleries , reopens April 13 after a massive 10-year rebuild .

At the heart of the `` new '' museum is its most treasured painting , `` The Night Watch , '' a group portrait of one of Amsterdam 's local militias , painted by Rembrandt van Rijn in 1642 , at the height of the Dutch Golden Age .

Read more : Rijksmuseum reopens after 10-year refurb

Architect Pierre Cuypers designed the building around the massive masterpiece -- it measures 11 feet by 14 feet -- in 1885 , and it is the only work to be returned to its original location in the radically revamped gallery .

`` Everything has changed , the only thing that has n't is ` The Night Watch ' , '' explains Wim Pijbes , the museum 's director . `` It is the altarpiece of the Rijksmuseum , the whole place is arranged around this beautiful masterpiece . ''

Visitors will approach Rembrandt 's painting through the cathedral-like entrance hall , filled with jewel-toned stained glass and extravagant wall decorations , and the restored Gallery of Honor , home to the Rijksmuseum 's collection of 17th century works .

Pieter Roelofs , curator of 17th century art , told CNN the arrangement `` shows off how important this painting is to the Dutch nation . It is the national treasure . ''

In keeping with the ethos of the new-look museum , `` The Night Watch '' is surrounded by other militia portraits of the era , giving the piece context but also showing just how innovative Rembrandt 's work was .

And there 's another hint as to just how well-loved the priceless painting is on the floor beneath it : The outline of a trap door . `` The Night Watch '' is the only picture in the gallery to have its own `` escape slide , '' designed in 1934 , to allow it to be swiftly moved out of danger in case of fire , or other threats .

Click on the picture above to reveal the artwork 's secrets .

@highlight

Amsterdam 's Rijksmuseum reopens after massive $ 489m , 10-year rebuilding program

@highlight

The ` altarpiece ' of the cathedral-like Gallery of Honor is Rembrandt 's ` The Night Watch '

@highlight

Curator Pieter Roelofs says the painting is ` the Dutch national treasure '